A power source switching circuit, includes a first and second contact, a first, second, and third relay. The first contact includes a first normally open main contact and a first normally closed auxiliary contact. The second contact includes a second normally open main contact and a second normally closed auxiliary contact. The first, second, third normally open contacts of the first, second, third relays, connected in series, are connected between three phrase lines of the main power source and the second normally closed auxiliary contact. The second normally closed auxiliary contact is connected to a zero line of the main power source. The first, second, third normally closed contacts, connected in parallel, are connected between three phrase lines of the auxiliary power source and the first normally closed auxiliary contact. The first normally closed auxiliary contact is connected to a zero line of the auxiliary power source.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A power source switching circuit, comprising: a first contact, the first contact comprises a first normally open main contact and a first normally closed auxiliary contact, the first normally open main contact configured to be connected between a main power source and a loader; a second contact, the second contact comprises a second normally open main contact and a second normally closed auxiliary contact, the second normally open main contact configured to be connected between an auxiliary power source and the loader; a first relay, and the first relay comprises a first normally open contact and a first normally closed contact; a second relay, and the second relay comprises a second normally open contact and a second normally closed contact; and a third relay, and the third relay comprises a third normally open contact and a third normally closed contact; wherein the first normally open contact, the second normally open contact, and the third normally open contact, connected in series, are configured to be connected between three phase lines of the main power source and the second normally closed auxiliary contact; the second normally closed auxiliary contact is configured to be connected to a zero line of the main power source; the first normally closed contact, the second normally closed contact, and the third normally closed contact, connected in parallel, are configured to be connected between three phase lines of the auxiliary power source and the first normally closed auxiliary contact; and the first normally closed auxiliary contact is configured to be connected to a zero line of the auxiliary power source.
2. A power source switching system, comprising: a main power source, and the main power source comprises three first phase lines and a first zero line; an auxiliary power source, and the auxiliary power source comprises three second phase lines and a second zero line; and a power source switching circuit, and the power source switching circuit comprises: a first contact, and the first contact comprises a first normally open main contact and a first normally closed auxiliary contact, and the first normally open main contact configured to be connected between the main power source and a loader; a second contact, and the second contact comprises a second normally open main contact and a second normally closed auxiliary contact, and the second normally open main contact configured to be connected between the auxiliary power source and the loader; a first relay, and the first relay comprises a first normally open contact and a first normally closed contact; a second relay, and the second relay comprises a second normally open contact and a second normally closed contact; and a third relay, and the third relay comprises a third normally open contact and a third normally closed contact; wherein the first normally open contact, the second normally open contact, and the third normally open contact, connected in series, are connected between the three first phase lines and the second normally closed auxiliary contact; the second normally closed auxiliary contact is connected to a zero line of the main power source; the first normally closed contact, the second normally closed contact, and the third normally closed contact, connected in parallel, are connected between three phase lines of the auxiliary power source and the first normally closed auxiliary contact; and the first normally closed auxiliary contact is connected to a zero line of the auxiliary power source.
3. The power source switching system of claim 2 , wherein the main power source is a three phase alternating current power source.
4. The power source switching system of claim 2 , wherein the auxiliary power source is a three phase alternating current power source.
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December 27, 2012
October 20, 2015
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